If you are talking about a final product to go inside the SDR-1000
then I agree, one board with all the stuff you need. But right now we
are in development mode, a system with individual boards is more
convenient specially when developing different projects.

The are advantages to having individual functions while doing
development such as;

1. The pieces can be used individually in other projects. Ie; Analog
board feeding a DSP processor board for standalone system, no PC.
2. If you want to try a different A/D you only need to change that
small board.
3. Need 4 channels? Just add a second analog board, it doesn't even
have to be the same kind of analog chips.

4. Nasty digital stuff is completely away from the sensitive analog components
Yes it cost a little more, but while developing it gives you more flexibility.
At 08:55 PM 12/15/2005, you wrote:

KD5NWA wrote:
> I have heard that the internal PLL has a lot of jitter, which is
> precisely what we are trying to avoid.
I was NOT proposing using the internal PLL of the FPGA.
> Personally I think the A/D, and D/A aught to be it's own little
> universe, in it's own little card, with it's own precise clock and
> it's only link to the Xylo is the I2C bus.
A two board (or more) "product" is going to cost more, be less reliable
and will offer no advantage. I'm not talking about using the Xylo board
for the end "product" at all which I think almost everyone agrees with.
You are possibly talking development, I'm talking about the end product
in my clocking suggestion. Sorry if we're not on the same page.
Don, AE5K
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Cecil Bayona
KD5NWA
www.qrpradio.com

"I fail to see why doing the same thing over and over and getting the
same results every time is insanity: I've almost proved it isn't;
only a few more tests now and I'm sure results will differ this time ... "